Time Correlations between the Two Sidebands of the Resonance Fluorescence Triplet

Abstract

A new type of time correlation analysis of resonance fluorescence is presented. A strontium atomic beam is excited by a 28-\AA{}A-off-resonance laser. The photons of the two sidebands of the fluorescence triplet are shown to be emitted in a well-defined time order. A simple interpretation of this effect is given which implies a quantum jump of the atom from the lower to the upper state through a multiphoton process.